scholarly journals Experimental and numerical simulation of buried pipelines subjected to large permanent ground displacements

2017 ◽  
Author(s):  
Άγγελος Τσάτσης
Keyword(s):  
Numerical Simulation ◽  
Buried Pipelines ◽  
Ground Displacements

[…] Η παρούσα Διδακτορική Διατριβή αποτελείται από δύο κύριες ενότητες. Η πρώτη ενότητα είναι αφιερωμένη στην απόκριση υπογείων αγωγών υποβαλλόμενων σε τεκτονική διάρρηξη κατακόρυφης βύθισης (κανονικά και ανάστροφα ρήγματα). Στόχος είναι η πλήρης προσομοίωση της διάρρηξης από το βραχώδες υπόβαθρο έως την επιφάνεια του εδάφους και η ταυτόχρονη μελέτη της δομητικής απόκρισης του αγωγού. Πλέον της ανελαστικής ανάλυσης του εδάφους και των συνθηκών επαφής εδάφους-αγωγού, ιδιαίτερη έμφαση δίδεται στην ορθή ανάλυση της εντόνως μη-γραμμικής απόκρισης του μεταλλικού κελύφους. Η δεύτερη ενότητα αναφέρεται στην απόκριση υπογείων αγωγών υποβαλλόμενων σε μεγάλες εδαφικές μετακινήσεις λόγω ενεργοποίησης περιστροφικής κατολίσθησης. Και για τις δύο (2) φορτίσεις καταρτήθηκε κατάλληλη αριθμητική μεθοδολογία η οποία εν συνεχεία βαθμονομήθηκε και επαληθεύτηκε έναντι πειραμάτων της βιβλιογραφίας αλλά και πειραμάτων μικρής κλίμακας που διεξήχθησαν στο Εργαστήριο Εδαφομηχανικής του Ε.Μ.Π. […]

scholarly journals A Study on Determining Time-Of-Flight Difference of Overlapping Ultrasonic Signal: Wave-Transform Network

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5140
Author(s):  
Zhipeng Li ◽  
Tong Wu ◽  
Wei Zhang ◽  
Xuyang Gao ◽  
Zhenqiu Yao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Arrival Time ◽  
Oil And Gas ◽  
Time Of Flight ◽  
Ultrasonic Signal ◽  
Signal Wave ◽  
Buried Pipelines ◽  
Ultrasonic Echo ◽  
Before And After ◽  
Novel Method

An ultrasonic sensors system is commonly used to measure the wall thickness of buried pipelines in the transportation of oil and gas. The key of the system is to precisely measure time-of-flight difference (TOFD) produced by the reflection of ultrasonic on the inner and outer surfaces of the pipelines. In this paper, based on deep learning, a novel method termed Wave-Transform Network is proposed to tackle the issues. The network consists of two parts: part 1 is designed to separate the potential overlapping ultrasonic echo signals generated from two surfaces, and part 2 is utilized to divide the sample points of each signal into two types corresponding to before and after the arrival time of ultrasonic echo, which can determine the time-of-flight (TOF) of each signal and calculate the thickness of pipelines. Numerical simulation and actual experiments are carried out, and the results show satisfactory performances.

Numerical Simulation on the Dynamic Response of Buried Pipelines Subjected to Blast Loads

2013 ◽  
Vol 671-674 ◽  
pp. 519-522 ◽  
Author(s):  
Guo Fu Xu ◽  
Zheng Dong Deng ◽  
Fei Fan Deng ◽  
Guo Bin Liu
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Dynamic Response ◽  
Buried Pipeline ◽  
Blast Loads ◽  
Buried Pipelines ◽  
Axis Direction ◽  
Ground Shock ◽  
Explosion Center

When the shock wave caused by explosion in geotechnical medium encountered buried pipeline, the buried pipeline may be destroyed. Use the LS-DYNA program to describe the deformation of buried pipelines under explosion ground shock. The results indicate that the process of the stress on pipe is instantaneous, and the back of buried pipelines against explosion center suffers greater instantaneous pulling stress in axis direction. The stress on the pipes, which is brought by the weaponary explosion, is involved with the distance between the pipe and explosion center and the diameter of pipe, among which the former involves greater. And the smaller pipe would get greater shock.

scholarly journals Experimental and numerical simulation on buried hot fuel oil pipelines in three modes flow regime considering temperature loss during a shutdown

2020 ◽  
pp. 345-345
Author(s):  
Mohsen Dehdarinejad ◽  
Morteza Behbahani-Nejad ◽  
Ebrahim Hajidavalloo
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Pour Point ◽  
Large Scale ◽  
Fuel Oil ◽  
Fluid Density ◽  
Temperature Dependent ◽  
Buried Pipelines ◽  
Temperature Loss ◽  
Oil Pipelines

Aiming to study the temperature distribution along buried pipelines containing hot fuel oil, a new large-scale laboratory is constructed from the perspective of the corresponding fluid thermophysical properties. Also, a modeling of the pipeline, and the soil around it, was performed along the pipeline for observation of all three modes of turbulent, laminarization, and laminar flow, which is validated by experimental results. Furthermore, the appropriate data are also gathered from the actual pipeline, 107 km of the 26? pipeline between Abadan Refinery and Mahshahr Port, and the results of the experiment and modeling are reconfirmed. The experiment shows that the viscosity and fluid density of fuel oil is strongly temperature-dependent. Many experiments are performed on the parameters affected by temperature according to their importance. The method chosen to simulate three flow modes along the pipeline shows less than 2% error in turbulent and laminar zones and reveals just a 3% error to experimental data in the laminar region. The maximum safe time during the stopping period of the pipeline (MSST) and holding fuel oil in it is calculated based on the pour point of fuel oil. This time is critical for the real pipeline in sudden shutdown and is calculated 41 hours.

scholarly journals Buried pipelines with bends: analytical verification against permanent ground displacements

2016 ◽  
Vol 53 (11) ◽  
pp. 1782-1793 ◽  
Author(s):  
Dimitris K. Karamitros ◽  
Christos Zoupantis ◽  
George D. Bouckovalas
Keyword(s):  
Practical Interest ◽  
Radius Of Curvature ◽  
Arbitrary Angle ◽  
Buried Pipelines ◽  
Analytical Methodology ◽  
Pipeline Segment ◽  
Pipeline Design ◽  
Equivalent Linear Analysis ◽  
Analytical Verification ◽  
Ground Displacements

Available analytical methodologies for the stress analysis of buried pipelines against large permanent ground displacements (PGDs) apply only to straight pipeline segments. Hence, a new methodology is proposed herein for the analytical computation of pipeline strains in bends of arbitrary angle and radius of curvature, located outside the PGD high-curvature zone, but within the pipeline’s unanchored length. The methodology is based on the equivalent-linear analysis of the bend, assuming that it will perform as an elastic arched beam subjected to uniformly distributed ultimate axial and transverse horizontal soil reactions. The end of the bend towards the PGD zone is subjected to an axial displacement, calculated on the basis of overall displacement compatibility along the pipeline, while the other end is restrained by the unanchored pipeline segment beyond the bend. Using this approach, the maximum axial force at the vicinity of the PGD zone can also be calculated and consequently used for the estimation of corresponding pipeline strains with any of the available numerical or analytical methodologies for straight pipeline segments. Parametric nonlinear finite element analyses are performed to verify the analytical methodology and also derive conclusions of practical interest regarding the effect of bends on pipeline design.

scholarly journals Study on Dynamic Strain Regularity and Influencing Factors of Shallow Buried Metal Pipe under Collapse Impact Load

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Min Wang ◽  
Mingshou Zhong ◽  
Yuan Long ◽  
Kai Ding ◽  
Xingbo Xie ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Impact Load ◽  
Simulation Method ◽  
Dynamic Strain ◽  
Stiffness Ratio ◽  
Buried Pipeline ◽  
Range Analysis ◽  
Buried Pipelines ◽  
Soil Stiffness ◽  
Metal Pipe

With the combination of model experiment and numerical simulation, we explore the effect of collapse height, weight, and pipe-soil stiffness ratio on dynamic strain of shallow buried metal pipe under the collapse impact load. By analyzing the strain at different measuring points of the buried pipeline, the strain law of the buried pipeline under the collapse impact load is obtained. Based on the range analysis and variance significance analysis, it was found that the pipe-soil stiffness ratio has a more significant impact on the dynamic strain of the buried pipeline under impact compared to the collapse height and the weight. Then, the numerical simulation method was used to further analyze the effect of pipe-soil stiffness ratio on the dynamic response of buried pipelines; the following conclusions are drawn: As the stiffness ratio of pipe-soil increases, the plastic stress and strain of the buried pipeline will decrease, and influence of the pipeline by the collapse impact is slighter.

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